Tracks can be protected, to prevent any alterations. When a track is protected:
Existing regions (and their contents) cannot be altered.
No recording is possible.
New regions cannot be created.
If the Track Protect button is not visible in the track list, you can display it using the Track Header Configuration dialog.
Clicking a Track Protect button toggles between Locked and Unlocked modes.
Command-clicking a Track Protect button in the track list protects all tracks in the currently selected display level (or folder). If tracks were already protected, they will be unprotected.